Once you redeem a preorder code for this game, it is bound to your player.dfprofile. If you happen to somehow delete this file (in which the dlc/savegames are stored basically) the content is gone. You can delete your individual savegames ingame without losing the dlc though.

Problem is GameSpy doesn't allow you to retrieve your lost dlc in any possible way. Using the code twice of course doesn't work either.

Sucks if you are unaware of that. So without a local backup there is no way to get it back. Because many people don't know this, we decided to make a save that includes all dlc for people who lost theirs.

So what that means is with Hunted: DF if you have a save game that has DLC unlocked you also are able to get that DLC?

I find it highly unlikely though if you use your legit keys for DLC that after you uninstall the game it is gone forever, I am sure it is tied to some sort of account like the original cd-key is.

But if the above is a quote from the developers then I can see why they might do this.

EDIT:

On closer inspection, it seems people who got the game from Direct2Drive or similar have been asking why their pre-order codes do not work any longer, and each have been sending people to steam staff as it was them who provided the codes.

Right, you just need the savegame to use the dlc. This even makes sense because I think all this dlc isn't downloaded, but hidden inside the game from the start. The code doesn't download anything new, it just unlocks the dlc in your player.dfprofile. And unless they patch it, there is no other way to unlock your dlc a 2nd time if you lose that file.

In my opinion they should just release all the dlc for free (as compensation for this mess) with an Update for the current MP issues.